Digitalizer, digital conversion method and capacitive touch panel device

Abstract

The invention discloses a digitalizer, a digital conversion method and a capacitive touch panel device, which is combined with a period counter with a phase digitizer to improve the resolution ratio of an output value. The digitalizer comprises a time control unit, the period counter, the phase digitizer and a computing circuit, wherein the time control unit is used for generating a first control signal according to a square wave signal and a default value; the period counter is used for generating a first digital signal according to a reference frequency signal and the first control signal; the phase digitizer is used for generating a second digital signal according to the phase difference between the square wave signal and the reference frequency signal; and the computing unit is used for generating an output digital signal according to the first digital signal and the second digital signal.

Description

technical field [0001] The present invention relates to a digitizing apparatus, in particular to a digitizing apparatus with high resolution and low cost. Background technique [0002] A general capacitive touch panel usually includes a waveform generator and a capacitance value digitization device, wherein the waveform generator generates an oscillating square wave with a corresponding period according to the equivalent capacitance value of each column of capacitors, and the capacitance value digitization device then According to the period of the oscillating square wave, a corresponding digital value is generated, and therefore, the digital value represents the magnitude of the equivalent capacitance. [0003] figure 1 It is a structural diagram of a traditional waveform generator. refer to figure 1 , the conventional waveform generator 120 includes two current sources (current source) IDAC1 and IDAC2 , an operational amplifier (Op-Amp) 121 and a comparator 122 . The c...

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Problems solved by technology

[0014] In actual application, the coordinate resolution of the capacitive touch panel depends on the resolution of the digitization of the capacitance value. Assuming that the system has a high-resolution requirement for the digitization of the capacitance value, if the above-mentioned analog-to-digital converter is implemented, the high-resolution The analog-to-digital converter with high rate (high number of digits) is expensive and difficult to implement; however, if the above-mentioned cycle counting method is implemented, a higher sampling frequency (reference frequency signal SC) and a longer sampling period must be used, but This also means that the circuit will have more power consumption and longer response time

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